The use of coherent or partially coherent light sources can have advantages in display or illumination over standard incoherent sources (lamps), in that they can achieve higher brightness, better reliability, and larger color gamut. However, with this increased coherence comes the issue of speckle interference. Speckle is due to interference of the light reflecting from the screen or target that causes variations in intensity that can be seen by the observer or instrument. High spatial frequency, intensity variations are typical and very undesirable for display or imaging applications.